Capless multiaxial screw and spinal fixation assembly and method

ABSTRACT

A bone fixation assembly and capless multi-axial screw system and method are shown. The assembly comprises a receiver having a rotary lock which in one embodiment includes a plurality of channels which urge and lock the elongated member to the screw using a bayonet type connection.

RELATED APPLICATION DATA

This application is a continuation-in-part of application Ser. No. 11/193,523, filed Jul. 29, 2005, which is incorporated herein by reference and made a part hereof.

BACKGROUND OF THE INVENTION

This invention relates to a capless multiaxial screw and spinal fixation assembly and method, particularly useful for fixing and/or aligning vertebrae of the spine. The invention permits multiple angular orientations of an elongated member or rod with respect to a screw that is screwed into a vertebra.

Various methods of spinal immobilization have been known and used in the past. The preferred treatment for spinal stabilization is immobilization of the joint by surgical fusion or anthrodesis. This method has been known since development in 1911 by Hibbs and Albe. However, in many cases, in particular cases involving fusion across the lumbosacral articulation and where there are many levels involved, pseudorarthrosis is a problem. It was discovered that immediate immobilization was necessary in order to allow a bony union to form. Post operative external immobilization, such as the use of splints and casts, was a favored method of treatment, however, as surgical techniques have become more sophisticated, various methods of internal and external fixation have been developed.

Internal fixation refers to therapeutic methods of stabilization which are wholly internal to the patient and include commonly known devices such as bone plates and pins. External fixation, in contrast, involves at least some portion of stabilization device which is external to the patient's body. Internal fixation is now the favored method of immobilization because the patient is allowed greater freedom with the elimination of the external portion of the device and the possibility of infection, such as a pin tract infection is reduced.

There have been numerous systems and methods developed in the past for correcting and stabilizing and aligning the spine for facilitating, for example, fusion at various levels or areas of the spine, such as those devices are shown in U.S. Pat. Nos. 4,085,744; 4,269,178; 4,805,602; 5,466,237; 5,474,555; 5,891,145; and 6,869,433 B2. Bone screws with a polyaxial head are commonly used in spine surgery today. They are used chiefly in the lumbar spine and screwed into bone (pedicle) posteriorly. The head of the screw is attached to the shaft of the screw by means of a ball and socket. The top of the screw is machined into a ball, and the head contains a socket into which the ball fits. The screw head further contains a receiver for receiving a separate rod. The rod is fastened to the screw head receiver via a threaded cap. The rod is then fastened to screws placed in adjacent vertebrae thus providing stabilization. The polyaxial head allows the rod to be placed in a variety of angles with respect to the screw allowing conformance to local anatomy.

When the threaded cap is tightened upon the rod, a frictional pressure is transmitted from the threaded cap to the rod thence to the top of the ball, thus locking the ball-in-socket and preventing motion after tightening has occurred. This concept is demonstrated in U.S. Pat. Nos. 5,466,237 and 5,474,555, which illustrate this type of screw.

U.S. Pat. No. 5,466,237 to Bird et al. discloses a bone screw having a spherical projection on the top of the bone screw. An externally threaded receiver member supports the bone screw and spinal rod on top of the spherical projection. An outer nut is tightened onto the receiver member to press the spinal rod against the spherical projection to accommodate various angular orientations of the bone screw relative to the rod.

In another approach shown in U.S. Pat. No. 4,946,458 to Harms, a spherical headed bone screw supported within separate halves of a receiving member. The bottom of the halves are held together by a retaining ring. The top of the receiver halves are compressed about the bone screw by nuts threaded onto a threaded spinal rod.

In still another approach taken by Harms et al. in U.S. Pat. No. 5,207,678, a receiver member is flexibly connected about a partially spherical head of a bone screw. Conical nuts on opposite sides of the receiver member threaded onto a threaded rod passing through the receiver. As the conical nuts are threaded toward each other, the receiver member flexibly compresses around the head of the bone screw to clamp the bone screw in its variable angular position. One detriment of the systems in the two Harms et al. patents is that the spinal rod must be threaded in order to accept the compression nuts.

U.S. Pat. No. 6,869,433 discloses the use of a pedicle screw assembly that comprises a screw having a head with a convex portion and a receiver that receives the head. The receiver also receives an elongated member, such as a spinal fixation rod. The receiver has a concave portion which has a radius of curvature which is less than the radius of curvature of the convex portion of the head whereby to create an interference fit between the convex portion of the head and the concave portion of the receiver. The device also includes an internal nut and external nut that compresses the rod against a pressure disc which in turn compresses the head convex portion of the screw into the receiver concave portion and locks the angular position of the receiver with respect to the screw.

One of the problems with the prior art devices is the number of parts and components, especially those components that utilize a threaded cap screw to secure the rod to the anchoring screw, whether internal or external, to fix the rod relative to the screw. Problems with the threaded fastener, that is, threaded cap or set screw, are numerous and include risk of cap loosening, loss of cap intra-operatively, cross threading, thread failure, failure of the cap in driving instrument and limitations upon torque application.

What is needed, therefore, is a system and method that provide a lock or connection between the rod and screw without the use of external nuts, screws, caps or threads of the type shown in the prior art.

SUMMARY OF THE INVENTION

The present invention improves the spinal fixation and the locking between an elongated member or rod and a screw.

One object of the invention is to provide a system and method that reduces or eliminates the need for external or internal caps or screws to lock the relative position of a rod to a screw.

Another object of the invention is to provide a simple bayonet-type connection that eliminates the fixation systems of the past and/or simplifies the spinal fixation procedure.

In one aspect, this invention discloses a capless multiaxial screw system comprising a receiver comprising a receiver end comprising a receiver bore for receiving a threaded portion of a screw having a screw head; and a sleeve having a sleeve end for situating against at least a portion of the screw head after the threaded portion is received in the receiver bore, the sleeve having a sleeve bore associated with the sleeve end; the receiver having a channel for receiving an elongated member; the sleeve being adapted to permit the elongated member to engage the at least of portion of the screw head when the elongated member is received in the channel and the receiver is rotated to a locked position.

In another aspect, this invention discloses a spinal fixation assembly comprising a receiver having a receiver bore for receiving a screw having a screw head and a receiver channel in communication with the receiver bore for receiving an elongated member; and a stabilizer dimensioned to be received in the receiver bore, the stabilizer having a stabilizer channel associated with a first end of the stabilizer for receiving the elongated member and a stabilizer bore through a second end of the stabilizer, the second end being adapted to permit direct contact between at least a portion of the screw head and the elongated member; the receiver being capable of rotating relative to the elongated member after the elongated member is received in the receiver channel to force the elongated member into contact with the at least a portion of the screw head.

In yet another aspect, this invention relates to a receiver for use with a polyaxial screw comprising a body having a bore; and a channel for receiving an elongated member and for compressing it into engagement with a screw head of the polyaxial screw when the receiver is rotated.

In still another aspect, this invention relates to a spinal fixation assembly comprising a receiver having a bore for receiving a screw having a screw head; and an intermediate member dimensioned to be received in the bore and having a first end and a second end; the receiver comprising an integral rotary lock for forcing and locking an elongated member directly against the screw head when the receiver is rotated.

In another aspect, this invention discloses a spinal fixation assembly comprising a receiver having an opening for receiving a screw having a screw head; and an intermediate member dimensioned to be received in the opening and having an intermediate member receiving channel for receiving an elongated member and a screw head receiving opening adapted to receive at least a portion of the screw head; the receiver comprising a receiver channel for receiving the elongated member, the receiver channel forcing the elongated member into contact with the screw head when the receiver is rotated from an unlocked position to a locked position.

In another aspect, this invention relates to a capless multiaxial screw system comprising a screw having a threaded portion and a screw head; a receiver having a receiver bore for receiving the threaded portion and a receiving channel for receiving an elongated member, the receiver further comprising a locking channel in communication with the receiving channel; an intermediate member adapted to be situated in the receiver bore, the intermediate member comprising an intermediate member bore for receiving at least a portion of the screw head; and the intermediate member bore being adapted to permit the at least a portion of the screw head to extend into the locking channel so that the elongated member may engage and compress against the at least a portion of the screw head when the elongated member is received in the receiving channel and the receiver is rotated.

In still another aspect, this invention discloses a capless multiaxial screw fixation assembly comprising a screw having a threaded portion and a screw head; a receiver having a bore for receiving the threaded portion and a receiving channel for receiving an elongated member, the receiving channel further comprising a locking channel in communication with the receiving channel; and a guide for situating in the bore, the guide comprising a second receiving channel associated with a first end of the guide and a seat area associated with a second end of the guide; the guide being adapted to permit at least a portion of the screw head to extend into the second receiving channel so that the elongated member may engage the screw head to lock the elongated member to the screw when the elongated member is received in the first and second receiving channels and the receiver is rotated from an unlocked position to a locked position.

In yet another aspect, this invention relates to a spinal fixation assembly comprising a receiver having a receiver bore for receiving a screw having a screw head, the receiver further comprising a locking channel and a receiving channel in communication with the locking channel; and an intermediate member dimensioned to be received in the receiver bore, the intermediate member comprising a body having a first end having an intermediate member channel and a second end having an intermediate member opening; the intermediate member opening being adapted to permit at least a portion of the screw head to engage an elongated member after the elongated member is received in the receiving, locking and intermediate member channels and the receiver is moved to a locked position.

These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawing and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary perspective view of a capless multiaxial screw and fixation assembly mounted on a spinal column having a plurality of vertebrae;

FIG. 2 is a perspective view of the system shown in FIG. 1;

FIG. 3 is an exploded fragmentary perspective view of the system shown in FIGS. 1 and 2;

FIG. 4 is a fragmentary perspective view illustrating a rod received in a receiving channel of a receiver;

FIG. 5 is a fragmentary plan view of the illustration shown in FIG. 4;

FIG. 6 is a fragmentary view similar to FIG. 4, but showing the receiver rotated approximately 30 degrees about its axis relative to the rod;

FIG. 7 is a fragmentary plan view similar to FIG. 5 and showing the receiver in the position illustrated in FIG. 6;

FIG. 8 is fragmentary perspective view showing the receiver in a fully locked position;

FIG. 9 is a plan view similar to FIGS. 5 and 7 showing the receiver in a fully locked position;

FIG. 10 is a view taken along the line 10-10 in FIG. 4;

FIG. 11 is a view illustrating the rod after it has been received in the channel of the receiver and supported above a bottom surface of a compression member;

FIG. 12 is a sectional view taken along the line 12-12 in FIG. 8;

FIG. 13 is a fragmentary view showing the rod in cross-section and in a fully locked position;

FIG. 14 is a fragmentary view illustrating various features of the locking channels;

FIG. 15 is a plan view showing a compression member received in a bore of the receiver and illustrating the aperture through which a tool may be inserted to rotate the screw head before the rod is positioned in a channel of both the receiver and the compression member;

FIG. 16A-16E are various views of the receiver in accordance with one illustration of the invention;

FIG. 17 is a sectional view of a compression member in accordance with one illustration of the invention;

FIG. 18 is a fragmentary sectional view of another illustration of the invention, showing a channel having walls that are generally non-planar to define an intermediate area for loosely capturing the rod;

FIG. 19 is a side elevation view of the embodiment shown in FIG. 18;

FIG. 20 is a fragmentary sectional view that has been rotated relative to FIGS. 18 and 19;

FIG. 21 is an elevational view rotated relative to FIG. 19;

FIGS. 22-24 are plan views illustrating rotational movement of the receiver relative to the rod;

FIGS. 25-27 are side elevation views that generally correspond to FIGS. 22-24, respectively, illustrating the receiver in various positions, but with the rod removed for ease of illustration and understanding;

FIGS. 28-30 are views similar to FIGS. 25-27, respectively, illustrating the receiver in various rotational positions relative to the rod as the rod is moved from a receiving position to a locked position;

FIGS. 31-33 are fragmentary sectional views somewhat enlarged and diagrammatic to simply illustrate the intermediate capturing step of receiving area for loosely capturing the rod in the receiver;

FIG. 34 is a diagrammatic view which is presented for purposes of illustrating various dimensions of the channels in the receiver or the second illustrative embodiment;

FIG. 35A is a perspective view of another embodiment of a capless multiaxial screw and fixation assembly in accordance with another embodiment of the invention;

FIG. 35B is a sectional view of the embodiment illustrated in FIG. 35A;

FIG. 35C is a perspective view of sleeve or guide used in the embodiment illustrated in FIG. 35A;

FIG. 35D is a sectional view taken along the line 35D-35D in FIG. 35C;

FIG. 35E is a plan or top view of a sleeve or guide in accordance with another embodiment of the invention;

FIG. 36A is a perspective fragmentary view of screw used in the embodiment illustrated in FIG. 35A;

FIG. 36B is a plan or top view of the polyaxial screw shown in FIG. 36A;

FIGS. 36C-36H illustrate other representative polyaxial screw head configurations that may be used to permit maximal polyaxial movement;

FIGS. 36I-36L illustrate various tools used to drive the screws shown in FIGS. 36A-36H;

FIGS. 37-42 are various views of the embodiments shown in FIG. 36A illustrating the rotation of the receiver relative to the rod and the guide or sleeve;

FIGS. 43-46 are fragmentary sectional views illustrating various features of the receiver in an unlocked position and a locked position;

FIGS. 47-48 illustrate the polyaxial tilting of the receiver and the rod engaging the screw head directly;

FIGS. 49-57 are various views illustrating various receiver positions with and without the rod and using the intermediate channel or embodiment of the type illustrated in FIGS. 18-34;

FIG. 58 is a fragmentary perspective view of the capless multiaxial screw fixation assembly in accordance with the embodiment illustrated in FIG. 35A mounted on the spinal column having the plurality of vertebra; and

FIG. 59 is an exploded fragmentary perspective view of the system shown in FIG. 58.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-3, a capless multi-axial screw and spinal fixation assembly 10 and method are shown. The assembly 10 comprises a screw 12 having a threaded portion 12 a and a head 12 b that in the embodiment being described, has a rounded profile or curvature, as best illustrated in FIGS. 3 and 10-13. The screw head 12 b comprises a hex female opening 12 c for receiving a tool (not shown) for screwing the screw 12 into an aperture 14 a of a spinal bone 14, such as a vertebra of a spine.

As illustrated in FIGS. 1 and 2, one feature of the invention is that it enables a user to fix a relative position of a plurality of vertebrae, such as vertebrae 14, 16 and 18 in FIG. 1, in a fixed and stabilized position.

The system 10 comprises a retainer or receiver 20 having a generally cylindrical receiver wall 20 c (FIG. 4) that defines an aperture or bore 22 that traverses or extends along a receiver axis A (FIG. 11) the entire length of the receiver 20, as best illustrated in FIGS. 4, 10, and 12. The receiver 20 comprises a first end 20 a and a second end 20 b, and although not shown, may comprise a chamfer 21 of about 45 degrees. It should be understood that the internal wall 20 c defines a seat 20 d toward the bottom of the receiver 20 (as viewed in FIGS. 10 and 15) that is arcuate or curved in cross section. The seat 20 d has a radius or curved surface R1 (FIG. 10). Note that a diameter or distance D1 (FIG. 10) of bore 22 at the end 20 b of the receiver or retainer 20 is slightly smaller than both a diameter or distance D2 (FIGS. 7 and 10) of the bore 22 at end 20 a and a diameter D3 (FIG. 12) of the rounded screw head 12 b so that it defines the receiver seat 20 d (FIGS. 10 and 15) for receiving or capturing the screw head 12 b. In this regard, the screw head 12 b has an end 12 b 1 that is configured and dimensioned to be received or captured in the seat 20 d and that can be rotated or screwed while in the bore 22 (FIGS. 10 and 15). The end 12 b 2 has a curved or arcuate shape that generally complements the shape of the seat 20 d to permit polyaxial and relative movement between the receiver 20 and screw 12.

As shown in FIGS. 3 and 11-13, the bore 22 receives the threaded portion 12 a of the screw 12 until the head 12 b is received in the seat 20 d (as illustrated in FIGS. 10-13). It should be understood that the seat 20 d cooperates with the end 12 b 1 of head 12 b and permits the retainer or receiver 20 to move polyaxially about a center of head 12 b so that position of the receiver 20 may be altered relative to the head 12 b of screw 12. This allows a user, such as a surgeon or physician, to change the polyaxial position of the receiver 20 relative to the screw 12 in order to adjust an angular position of an elongated member or rod 24 relative to, for example, the vertebrae 14, 16 and 18 illustrated in FIG. 1. The rod 24 may be any suitable shape in cross section, such as circular, hexagonal, octagonal, polygonal or the like.

Note that the receiver 20 comprises a receiving channel or slot 26 (FIG. 15) defined by wall surfaces 21 a, 21 b, 21 c and 21 d (FIG. 4). The receiver 20 further comprises a lock, locking means, locking channel, or rotary lock 28 (FIGS. 11 and 12) which is integral with the receiver 20. In the embodiment being described, the receiver 20 is manufactured of titanium and is machined to provide the receiving channel 26, lock 28 and the bore 22 using conventional machining techniques. Other potential materials include biocompatible load bearing material, such as metals, metal alloys, carbon fibers, composites, plastics or hybrid materials.

In one embodiment, the lock 28 cooperates and is in communication with the receiving channel 26 to provide a continuous channel 30 for receiving the elongated member or rod 24. The lock 28 cooperates with the receiving channel 26 and urges rod 24 toward the screw head 12 b and vertebra, such as one of the vertebra 14-18 in FIG. 1, when the receiver 20 is rotated in a clockwise direction (as viewed in FIG. 3). The continuous channel 30 comprises a first channel 32, the channel 26, and the second channel 34. The lock 28 and continuous channel 30 provides a bayonet-type connection for coupling or fixing the receiver 20, the rod 24 and screw 12 together in the manner described herein.

Note that the lock 28 comprises the first channel 32 and a second channel 34 (FIGS. 12 and 13) that extend or spiral, as illustrated in FIGS. 16A-16E, about the receiver axis A (FIG. 11) of receiver 20. The first and second channels 32 and 34 generally spiral or revolve from the first end 20 a of receiver 20 toward the second end 20 b, as shown in FIGS. 10-13 and 16A-16D. Thus, in the embodiment being described, the first and second channels 32 and 34 are non-linear and spiral or revolve in a general helix about the axis A of the receiver 20. In the illustration, the channels 32 and 34 spiral or revolve in the same direction about the axis A, as shown in FIGS. 16A-16D. Note that the channels 32 and 34 are in communication with both the receiver bore 22 and receiving channel 26 of receiver 20. During operation, the channels 32 (FIG. 11) and 34 (FIG. 12) receive the rod 24 after it has been received in channel 26 and urge or force the rod 24 toward the screw head 12 b and vertebra, such as vertebra 14 in FIG. 1, when the receiver 20 is rotated in a clockwise direction in the illustration being described.

As illustrated in FIGS. 11 and 16A, the first channel 32 is defined by a first surface or wall 20 e, a generally opposing second surface or wall 20 g, and a third surface wall 20 f that joins the walls 20 e and 20 g in the receiver 20. A fourth surface or wall 20 h, a generally opposing fifth wall 20 i, and a sixth surface or wall 20 j that joins walls 20 h and 20 i cooperate to define the second channel 34 (FIGS. 12 and 16D). Note that the walls 20 e and 20 g are generally parallel and walls 20 h and 20 i are generally parallel. In the illustration being described, the walls 20 e and 20 g and 20 h and 20 i are generally planar and have generally constant distance D4 (FIG. 13) and D5 (FIGS. 11 and 12) therebetween. However, in the illustration described later herein relative to FIGS. 18-32, the opposing walls 20 e, 20 g, 20 h and 20 i may be non-planar so that the distance or dimensions D9 and D10 vary along the length of the channels 32 and 34.

The channels 32 and 34 generally lay in planes P1 and P2 that are at the angles C (FIG. 14) and D, respectively, relative to the axis A of the receiver 20. As described later herein, the walls 20 e and 20 h engage and cam against the rod 24 and force or urge it downward (as viewed in FIGS. 10-15) in response to the rotary movement of the receiver 20. In another embodiment described later herein, the walls 20 e and 20 g and walls 20 h and 20 i may comprise a curved or arcuate area and may cooperate to define an intermediate rod capturing area, as described below relative to FIGS. 18-34.

As illustrated in FIGS. 4 and 11, note that the channel 32 is defined by the walls 20 e, 20 f, 20 g and generally curved or arcuate wall portion 50 that couples wall 20 g to surface 21 b (FIGS. 4 and 16A) of channel 26. The generally curved arcuate wall portion 50 also generally defines an intersection or transition from the receiving channel 26 to the first locking channel 32 of lock 28. The channel 34 is defined by 20 h, 20 i and 20 j and a third generally curved or arcuate wall 52 that joins the wall 20 i to walls 21 d (FIGS. 4 and 16C). The wall 52 provides an intersection or transition between channel 26 and the second locking channel 34. Notice that the wall portions 20 f (FIG. 11) and 20 j (FIG. 12) also each have a radius of curvature that generally complements the radius of curvature or circumference of the rod 24 so that when the rod 24 is moved from the unlocked position (illustrated in FIGS. 4, 5, 10 and 11) to a locked position (illustrated in FIGS. 8, 9, 12 and 13), the rod 24 is received and positioned against the wall portions 20 f and 20 j as shown.

The system 10 may further comprise a compression member 40 (FIGS. 3 and 17). The compression member 40 comprises a wall 40 a that defines a second generally U-shaped receiving channel 42. The compression member 40 also comprises a frusto-conical seat or concave area 41 (FIGS. 10 and 17), defined by a tapered wall or surface 40 b, that engages the rounded shape of the end 12 b 1 (FIG. 3) of screw head 12 b. Although not shown, the system 10 could be provided without the compression member 40, so that the rod 24 would engage the screw head 12 b directly, for example, when the receiver 20 is rotated as described later herein.

The compression member 40 comprises a length D6 (FIGS. 3 and 17) and a diameter D7 (FIG. 17) dimensioned to be received in the bore 22 as shown. The channel 42 defined by wall 40 a comprises a bottom surface 40 c. The channel 42 is generally U-shaped in cross section and has a width or dimension D8 (FIGS. 3, 7 and 17) and surface 40 c comprises a radius of curvature R5 (FIG. 17) that generally complements or is slightly larger than the circumference D9 (FIG. 3) of the rod 24.

During operation, the compression member 40 is urged downward (as shown in FIGS. 10-13) in response to the rotary movement of the receiver 20. The rod 24 engages the bottom surface 40 c (FIGS. 12 and 17) of channel 42 of compression member 40. This in turn causes surface 40 b to engage and apply a compressive force against the end 12 b 1 of screw head 12 b as the rod 24 is driven in the downward direction (as viewed in FIGS. 10-13) and into the second channel 42. This movement forces and compresses the seat 20 d against the end 12 b 2 of screw head 12 b of the receiver 20, thereby locking the screw head 12 b to the rod 24 and fixing the relationship of the receiver 20 relative to the screw head 12 b.

Note that the compression member 40 (FIG. 17) also comprises a bore or aperture 43 defined by wall 40 d. The bore 43 has a dimension or diameter D10 (FIG. 17). A surgeon or physician may insert a tool, such as a hex head screwdriver (not shown), through channel 26, through bore 22 of receiver 20 and through the bore 43 and into the hex female opening 12 c (FIG. 15), for example, to tighten or loosen the screw 12. Thus, it should be understood, as illustrated in FIG. 15, that the hex female opening 12 c of screw 12 b is accessible after the screw 12 is inserted through the bone 22 and compression member 40 is situated in the bore 22.

Referring back to FIGS. 10-16E, the receiving channel 26 (FIG. 11) of receiver 20 extends from an end 20 a of receiver 20 in an axial direction and lies in a plane P3 (FIG. 15) that is generally planar and extends downward along the axis A (as viewed in FIG. 14). In contrast, the lock 28 defined by the locking channels 32 and 34 revolve, spiral or extend laterally or radially at distances that are generally constant relative to axis A and that vary, such as increase, relative to end 20 a of receiver 20. As mentioned earlier, each of the channels 32 and 34 spiral in a general helix downward from the receiving channel 26 and about the axis A of the receiver 20 as shown in FIGS. 10-13 and 16A-16D. Note that the channels 32 and 34 lay in the planes P1 and P2 (FIG. 14), respectively, that intersect axis A at the predetermined angles indicated by double arrows C and D. The predetermined angles C and D are acute angles in the embodiment being described.

As shown in FIGS. 16A and 16B, the channel 32 is inclined relative to a radial line of receiver 20 at a third angle (indicated by double arrow E in FIG. 16A) relative to end 20 a. Channel 34 is also inclined relative to a radial line at a fourth angle F (FIG. 16B). Although not shown, it is contemplated that other designs, configurations or arrangements of channels 32 and 34 and the lock 28 may be provided, such as channels (not shown) that extend about axis A, but that do not spiral and/or that are not at the inclined angles E and F, such as channels that extend at distances that are generally constant relative to end 20 a.

An operation or method regarding this illustration will now be described. As illustrated in FIGS. 3-9 and 15, the screw 12, together with receiver 20 are screwed into vertebra 14 during which a physician or surgeon screws the threaded portion 12 b of screw 12 in the aperture 14 a of the vertebra 14 using a tool (not shown), such as a hex wrench or screwdriver (not shown), that is inserted through channel 26, bore 22 and bore 43. In one embodiment, the receiver 20, screw 12 and compression member 40 may be provided in a pre-assembled unit prior to surgery, so no assembly is required by the physician. The screw 12 is screwed substantially all the way into vertebrae 14, but is left with space between the receiver 20 and vertebrae 14 so that an angular or polyaxial position of the receiver 20 may be adjusted or changed during the operation.

The channel 26 of receiver 20 and channel 42 of compression member 40 are provided or arranged in a common plane P3, as shown in FIGS. 4, 5 and 15. The surgeon then places the rod 24 into the channels 26 and 42 and adjusts the multi-axial or polyaxial position of the receiver 20 relative to the rod 24. As mentioned earlier, the channel 26 and bores 22 (FIG. 10) and 43 (FIG. 17) provide a continuous opening or area 49 through which the physician or surgeon may insert a tool, such as a hex tool, to turn, rotate and/or tighten or loosen the screw 12 in the desired direction prior to placing the rod 24 into channel 26. At this point, the rod 24 remains in an unlocked position.

Note that the rod 24 is supported by and between the arcuate or rounded wall portions 50 and 52, which causes the rod 24 to be situated above the bottom surface 40 c of the channel 42 of compression member 40, as illustrated in FIGS. 10 and 11. Note that the arcuate or curved wall portions 50 and 52 each comprise a radius of curvatures R2 (FIGS. 11, 14 and 16 a) and R3 (FIGS. 13 and 14), respectively, that generally complements or is larger than a radius of curvature or circumference of the rod 24, as illustrated in FIGS. 11 and 13.

The camming or bayonet type action of the rotary lock 28 on receiver 20 forces the rod 24 in an axial direction parallel with axis A of receiver 20 when the receiver 20 is turned or rotated with a tool, such as a screwdriver (not shown), placed in channel 26, as illustrated in FIGS. 6 and 7. This rotary movement or action forces the rod 24 downward (as viewed in FIG. 10) and into the channels 32 and 34. As the receiver 20 is rotated further, as shown in FIGS. 8 and 9, the walls 20 e and 20 g (FIG. 11) of channel 32 and walls 20 h and 20 i (FIG. 12) of channel 34 act upon, force or urge the rod 24 downward (as viewed in FIGS. 10-13) and into the second channel 42 of compression member 40 until it engages the surface 40 c of compression member 40. As the receiver 20 is rotated further, the rod 24 urges the compression member 40 toward the screw head 12 b 1 and forces wall 40 b of the compression member 40 against the screw head 12 b of screw 12 with a compressive force which causes the screw head 12 b to become fastened or locked to the rod 24, thereby fixing the receiver 20 and rod 24 to the screw 12.

It should be appreciated that when the rod 24 is in the locked position shown in FIGS. 8, 9, 12 and 13, the rod 24 engages surfaces 20 e, 20 f, and 20 g of channel 32 and surfaces 20 h, 20 i and 20 j of channel 34 and surface 40 c of second channel 42. The seat 40 d of compression member 40 engages screw head 12 b 2. These surfaces cooperate to retain rod 24 in the locked position. The surfaces 20 f and 20 j comprise a radius of curvature R4 of about Φ.100-Φ.130 inch. A raised detent portion or bump 59 (which is only shown in FIG. 13 for ease of illustration) may be provided in each channel 32 and 34, as shown in FIG. 13 relative to channel 32. The detent 59 is provided to facilitate retaining the rod 24 in the locked position.

Thus, as illustrated in FIGS. 1, 2 and 4-9, a surgeon may use one or a plurality of spinal fixation assemblies 10 during a spinal fixation procedure. For example, the surgeon may use a plurality receivers 20 and screws 12 with one rod 24, as illustrated in FIGS. 1 and 2. In the illustration, the surgeon screws the screws 12 into a plurality of vertebrae, such as vertebrae 14, 16 and 18 illustrated in FIG. 1, and generally aligns the channels 26 of receivers 20. The surgeon then inserts the tool, such as a hex tool (not shown), through bores 22 and 43 and into female slot 12 c in screw head 12 and screws the screw 12 until the bottom 20 b of the receiver 20 engages or is proximately located against its respective vertebra.

If the compression member 40 is being used, compression member 40 is located in each bore 22 of each receiver 20 and generally aligns the channels 42 and 26, as illustrated in FIGS. 4, 10 and 15. It should be understood that when the spinal fixation assembly 10 is in the unlocked position, the channels 26 and 42 are generally parallel or lie in the common plane P3 as shown in FIG. 15. The rod 24 is then placed in channel 26, whereupon it becomes supported by walls 50 and 52 (FIG. 4) and by wall portions 50 and 52 (FIGS. 4 and 11). This causes rod 24 to be supported slightly above the bottom 40 c of channel 42 of receiver 40, as mentioned earlier and as illustrated in FIGS. 10 and 11.

At this point in the procedure, the surgeon aligns the rod 24 in the receiver 20 to the desired position relative to the spine, vertebrae and other receivers 20 that are being used. He positions the rod 24 and polyaxial or angular position of each receiver(s) 20 relative thereto. It should be understood that the screws and position of the vertebrae, such as vertebrae 14-18, relative to each other may also be adjusted. Once the bones 14-18 are adjusted and angular or polyaxial position of each receiver 20 is adjusted, the surgeon locks each receiver 20 to rod 24 by rotating or turning the receiver 20 with a tool, such as a screwdriver (not shown), placed in slot 26. This causes the receivers 20 to become fixed or locked onto their respective screws 12 and the spinal bones 14-18 (FIG. 1) to become aligned and fixed into the desired position.

It should be understood that before the rod 24 is placed in the receiving channel 26 and the receiver 20 is rotated, the surgeon may tighten one or more screws 12 to a tighter or fixed seated position by situating the tool, such as a hex wrench (not shown), through the aperture 43 (FIG. 15) defined by the wall 40 d of the compression member 40 and into the hexagonal female slot 12 c in the screw head 12 b. After the screw 12 is tightened to the desired tightness or torque, the surgeon places the rod 24 into the channels 26 and 42 (FIGS. 4, 5, 10 and 11) of the one or more of the receivers 20 being used.

As mentioned, the surgeon rotates the receiver 20 about its axis, as illustrated in FIGS. 3, 6 and 7 using a tool, such as a screwdriver (not shown), in the clockwise direction, as illustrated in FIGS. 6 and 7. During this rotation of receiver 20, the compression member 40 and rod 24 do not rotate. As alluded to earlier, walls 20 e and 20 g (FIG. 11) and walls 20 h and 20 i (FIG. 12) urge the rod 24 toward the bottom of channels 32 and 34 and urge the rod 24 to move downward (as viewed in FIGS. 10 and 12) toward the surface 40 c or bottom of the channel 42 where it engages the surface 40 c, as illustrated in FIGS. 4-9 and 10-13. The rod 24 is also supported by and compresses against the surface 40 c of compression member 40. The seat 40 d is caused to engage the screw head 12 b 2.

Thus, when it is desired to lock the receiver 20 and the screw 12 to the rod 24, the surgeon rotates the receiver 20 in the clockwise direction, as illustrated in FIGS. 6 and 7, using the conventional tool, such as a regular screwdriver. The receiver 20 is rotated until it is moved from the unlocked to the locked position, as illustrated in FIGS. 8, 9, 12 and 13. Note that in the locked position, the rod 24 is received and engages the walls 20 f and 20 j associated with the ends of channels 32 and 34, respectively.

Thus, it should be understood that when receiver 20 is rotated, the walls 20 e and 20 h provide the camming force necessary to cam and urge the rod 24 against the receiver 40. This, in turn, causes the surface or wall 40 b of receiver 40 to compress and lock against the end portion 12 b 2 (FIG. 3) of screw head 12 b. The wall 40 b of compression member 40 cooperates with the curved seat defined by wall 20 d (FIG. 10) and traps or locks the screw head 12 b to the rod 24.

As illustrated in FIGS. 8, 9, 12 and 13, notice that the channel 26 lies in an imaginary plane that is generally perpendicular to the imaginary plane in which the channel 42 and an axis of rod 24 when the receiver 20 is in the locked position.

It should be appreciated from the foregoing that the receiving channel 26 is in communication with the channels 32 and 34 of lock 28 and that the lock 28 cooperates with the rod 24 to not only lock the rod 24 to the screw 12, but also to fix a position of the vertebrae 14, 16 and 18.

When it is desired to unlock the rod 24 from the screw 12, the surgeon simply rotates the receiver 20 in a counterclockwise direction in the illustration and reverses the procedure.

Referring now to FIGS. 18-34, another illustrative embodiment is shown. Those parts that are the same as the parts relative to FIGS. 1-17 have been labeled with the same part number, except that the part numbers in the embodiment described in FIGS. 18-34 have a prime mark (“′”) associated therewith. The FIGS. 31-34 are diagrammatic enlarged sectional views for ease of illustration.

Note in the embodiment in FIGS. 18-34, the receiver 20′ comprises channels 32′ and 34′ that each have a cross-sectional dimension that varies over the length of the channels 32′ and 34′ to provide an intermediate holding area 60 where the rod 24′ is loosely captured in the channels 32′ and 34′. The channels 32′ and 34′ each have an introducing area 60 a, an intermediate holding or receiving area 60 b and a locking area 60 c. For ease of illustration and description, the receiving area 60 b will be described relative to channel 32′; however, it should be understood that the channel 34′ in the second illustration comprises substantially the same configuration.

It should be appreciated that the intermediate area 60 b in the channels 32′ and 34′ enable an intermediate step between initial rod 24′ insertion and final rod 24′ locking. In other words, this is a rod 24′ capturing step during which the rod 24′ is loosely captured in the receiver 20′, but it is not rigidly locked into place against screw 12′ yet. This allows the surgeon greater ease and flexibility when he adjusts the screws 12′ position with respect to the rod 24′ while the rod 24′ is in place. For example, the surgeon may move the screws 12′ closer together (compression) or In the illustration being described, the intermediate capturing step is accomplished by rotating the receiver 20′ partially, such as approximately 30 degrees in the illustration as shown in FIGS. 23, 26 and 29, which forces the rod 24′ from the introducing area 60 a into the intermediate area 60 b.

The introduction area comprises an associated dimension D13 (FIG. 34) and the locking area 60 c has an associated dimension D14 (FIG. 34). The intermediate area 60 b has an associated intermediate dimension D15 (FIG. 34) between the wall 62 and wall 64 that is slightly larger than the diameter of the rod 24′ and the dimensions D13 and D14 associated with the introduction area 60 a and locking area 60 c, respectively. It is dimensioned to accommodate the rod 24′ and to capture the rod 24′ loosely so that the rod 24′ can easily slide between the walls 62 and 64 and is not locked. This facilitates the surgeon adjusting a position of the screws 12′ in vertebrae, such as vertebrae 14′-18′, relative to a position of the rod 24. Once the screws 12′ are adjusted to the desired position, the physician or surgeon may then lock the receiver 20′ onto the screw 12′ by inserting a tool, such as a screwdriver (not shown), into the slot 26′ and rotate the receiver 20′ in the clockwise direction as illustrated in FIGS. 22-30.

In the illustration shown in FIGS. 31-34, the channel 32′ is defined by a wall 62, a generally opposing second wall 64 and a joining wall 63 that joins walls 62 and 64 as shown. Note that unlike the embodiment described relative to FIGS. 1-17, the channel wall 62 has a first wall portion 62 a, a second wall portion 62 b and an intermediate wall portion 62 c that couples the wall portions 62 a and 62 b as shown. The opposing channel wall 64 comprises the first wall portion 64 a, a second wall portion 64 b and an intermediate wall portion 64 c that couples the first and second wall portions 64 a and 64 b as shown. In this regard, note that an intersection 66 is defined between the wall portions 64 a and 64 c. A second intersection 68 is defined between the wall portion 62 b and 62 c as shown. The intersections 66 and 68 generally define an entrance to the intermediate area 60. The intermediate wall portions 62 c and 64 c cooperate to define the intermediate area 60 b which receives the rod 24′ and loosely captures the rod 24′ in the receiver 20′.

The channels 32′ and 34′ are configured such that they comprise or define the introduction area 60 a for receiving the rod 24′ in the receiver 20′, as illustrated in FIGS. 22, 25 and 28. The first wall portion 64 a provides a ramp 64 a 1 for directing the rod 24′ into the intermediate area 60 b when the receiver 20′ is rotated about 20-40 degrees as shown in FIGS. 23, 26 and 29. As shown in the illustration, the surfaces 62 and 64 are not generally planar and have areas, such as intermediate wall portions 62 c and 64 c that are curved or recessed to facilitate defining the intermediate area 60 b.

During a surgical procedure, the surgeon may make the desired adjustments of the rod 24′ relative to the screws 12′ and vertebrae 14′-18′ while the rod 24′ is loosely captured in the intermediate area 60 b. The surgeon then uses the tool, such as a screwdriver (not shown), to rotate the receiver 20′ to the locked position shown in FIGS. 24, 27 and 29. Similar to the embodiment described earlier herein relative to FIGS. 1-17, the receiver 20′ urges or forces the rod 24′ from the intermediate area 60 b to the locking area 60 c. The rod 24′ becomes situated in the locking area 60 c, whereupon the rod 24′ becomes locked therein. Note that the distance or dimension D12 (FIG. 8) between the second wall portions 64 b and 62 b is substantially the same or may be smaller than the diameter of the rod 24′. As the receiver 20′ is rotated in the clockwise direction in the illustration being described, the wall 62 slightly deflects upward (as viewed in FIG. 31, for example) to permit the rod 24 to be captured and locked in the locking area 60 c. Note that a wall portions 62, 63 and 64 comprises various radii of curvature R5-R9 having the illustrative dimensions or ranges of dimensions set forth in the Table I below. For example, the radius of curvature R8 generally corresponds to the cross sectional circumference of the rod 24′ so that the rod 24′ becomes captured in the locking area 60 c. As in the prior illustration, the detent 59 (FIG. 33) may be provided in channels 60 and 62 to further facilitate retaining the rod 24′ in the locking area 60 c.

Advantageously, this system and method facilitates providing a locking receiver 20 that reduces or eliminates the need for threading, internally or externally.

Advantageously, the immediate areas 60 b of channels 32′ and 34′ of the second embodiment are dimensioned and configured to facilitate locking the rod 24′ onto the screws 12′ while permitting ease of adjustment between the receiver 20′ and the rod 24′ when the rod 24′ and receiver 20′ are situated in the intermediate area 60 b′, as illustrated in FIGS. 23, 26 and 29.

In the embodiments being described, the rod 24, screw 12, receiver 20 and compression member 40 are all made of titanium alloy. Other materials may be used such as metals, metal alloys, carbon fibers, composites, plastics or hybrid materials.

For example, the screw 12 may have a length D11 (FIG. 3) ranging from 10 mm-60 mm, and the receiver 20 may have a diameter D12 (FIG. 8) ranging between 2 mm-10 mm. The compression member 40 may define the channel 42 having the width D8 ranging between 2 mm-12 mm. The channels 32 and 34 may comprise dimensions D5, D6 (FIGS. 3 and 17) ranging between 2 mm-10 mm. It should be understood, however, the other shapes and dimensions may be used without departing from the true spirit and scope of the invention.

Referring now to FIGS. 35-59, another illustrative embodiment is shown. As with prior embodiments, those parts that are the same or similar to the parts shown and described relative to FIGS. 1-34 have been labeled with the same part number, except that the part numbers described in FIGS. 35-59 have a double prime number (“″”). As with the prior embodiments, the FIGS. 35-59 are diagrammatic in large sectional views for ease of illustration.

In the embodiment being described, an assembly or system 100″ is shown. As illustrated in FIGS. 58 and 59, the assembly 100″ may be used alone or in combination with other assemblies 100″, with one or more of the assemblies 10 of the embodiments described earlier herein, or with other spinal fixation devices or assemblies (not shown). As with prior embodiments, the function of the assembly is to fix or secure one or more bones, such as the vertebrae 14″, 16″ and 18″ in the spinal column illustrated in FIG. 58, in a fixed and stabilized position relative to each other. As with the prior embodiments, it should be understood that the embodiment could be used in any environment where it is desired to fix and stabilize one or more bones or bone segments together.

In the embodiment illustrated in FIGS. 35-59, note that the receiver 20″ is substantially the same as in the prior embodiments shown and described relative to FIGS. 1-34. Also, it should be understood as with the embodiments illustrated in FIGS. 1-16E, the embodiment could comprise a substantially straight or planar channel 32 and 34, alternatively, it could comprise the stepped or multidimensional channels 32′ and 34′ (FIGS. 17-34) in receiver 20′. The channels 32′ and 34′ have a cross-sectional dimension that varies over the length of the channels 32′ and 34′ to provide the intermediate holding area 60′ where the elongated member or rod 24′ is loosely captured in the channels 32′ and 34′. As mentioned earlier, the channels 32′ and 34′ each have the introducing area 60 a′, the intermediate holding or receiving area 60 b′ and the locking area 60 c′. The channels 32′ and 34′ of the embodiment illustrated in FIGS. 18-34 receive the rod 24′ and facilitate positioning of the rod 24′ to the spinal bones, such as bones 14′, 16′ and 18′, prior to the receiver 20′ being rotated to the locked position as being described herein. Channel 32″ and 34″ may have configurations that are the same or similar to the channel 32, 32′, 34, and 34′.

Referring now to FIGS. 35A and 35B, the system 100″ comprises a stabilizer, intermediate member, second receiver, guide or sleeve, which shall be referred to as guide or sleeve 104″ for ease of description, rather than a compression member 40″ of the type shown in FIGS. 1-34. The guide or sleeve 104″ is received in the bore 22″ of receiver 20″ and is adapted to receive the rod 24″, which may be cylindrical and elongated as illustrated. In the embodiment illustrated in FIGS. 35A-59, it should be understood that the sleeve 104″ is adapted and dimensioned to be received in the aperture or bore 22″ defined by the receiver wall 20 c″. The guide 104″ is a guide or sleeve that is slidable and rotatable in the bore 22″.

The guide 104″ comprises or defines a bore 110″ (FIGS. 35A and 35E) in communication with a channel 121″ that receives the rod 24″ and facilitates aligning the rod 24″ in the receiver 20″. In this regard, the sleeve 104″ guides the rod 24″ into the receiving channel or slot 26″ of the receiver 20″. After the receiver 20″ is rotated as described herein, the rod 24″ is cammed, urged or moved toward a head 102 a″ of a polyaxial screw 102″ when the receiver 20″ is rotated to the locked position illustrated in FIGS. 45 and 46. Unlike the embodiment of FIG. 1, note that the screw 102″ has a ball or head 102 a″ that has a full radius. The full radius and bore 110″ are adapted or dimensioned such that at least a part of the head 102 a″ extends into the bore 110″. The operation and use of the assembly 100″ will be described in more detail later herein.

It should be understood that in this illustrative embodiment, the guide or sleeve 104″ does not function as a compression member like the compression member 40 and 40′ described earlier herein. Thus, one feature of this embodiment is that the rod 24″ engages and compresses directly against at least a portion of the head 102 a″ after the receiver 20″ is rotated to the locked position as described herein.

The sleeve or guide 104″ comprises a first wall portion 112″ and a generally opposed second wall portion 114″ that are curved about an axis B (FIG. 35B) of the guide 104″ (FIG. 35B). The guide or sleeve 104″ comprises generally cylindrical joining portions 117″ and 119″ that join the first and second wall portions 112″ and 114″ as illustrated in FIG. 35A. The wall portions 112″ and 114″ cooperate with the joining portions 117″ and 119″ to define the channel 121″. A pair of edges 112 a″ and 114 a″ (FIG. 35C) cooperate with joining portion 119″ to define a first channel opening 111″ to channel 121″. A second pair of edges 112 b″ and 114 b″ cooperate with joining portion 117″ to define a second channel opening 113″ to the opening 121″ for receiving the rod 24″.

The guide or sleeve 104″ comprises the bore 110″ having an inner diameter D16 (FIG. 35D). As illustrated in FIG. 35D, the wall portions 112″ and 114″ have inner surfaces 112 c″ and 114 c″, respectively, that lie in a generally cylindrical or curved plane and have a diameter D17 (FIG. 35D) that generally corresponds to a diameter of bore 110″. In the illustration being described, the channel 121″ has a channel width D18 (FIG. 35E) that generally corresponds to the diameter of the bore 110″. Unlike the embodiment illustrated in FIG. 17 described earlier herein, notice that the bore 110″ is in fluid communication with the channel 121″ and has the dimension D16 that generally corresponds to dimension D18. Thus, in the illustration being described, the bore 110″ has the dimension B16 (FIG. 35D) that is generally constant along its length and the diameter of the bore 110″ generally corresponds or is smaller than the distance between walls 112″ and 114″. In contrast, in the embodiment of FIGS. 1-34, the compression member 40″ comprises the wall 40 b″ that is curved or tapered inwardly and the dimension D10 is smaller than the dimension D8.

Notice that the first wall portion 112″ comprises a first end 112 d″ having a chamfer surface and the second wall portion 114″ comprises a second end 114 d″ having a chamfer surface as shown. The chamfer ends 112 d″ and 114 d″ facilitate guiding the rod 24″ into the receiving area 22″ and channel 121″ as described herein.

A second end 104 b″ (FIG. 35D) of the receiver 104″ comprises a surface 105″ in the wall portions 112″ and 114″ and the joining portions 117″ and 119″ that define a generally continuous frusto-conical surface in cross-section that extends around the bore 110″, as shown in FIGS. 35A and 35E. Alternatively, surface 105″ could comprise a curved, semispherical or spherical shape in cross-section or otherwise be shaped to complement a shape of the screw head 102 a″.

The first wall portion 112″ and generally opposed second wall portion 114″ have outer surfaces 112 d″ and 114 d″ that lie in a cylindrical or circumferential plane that is generally cylindrical and adapted and dimensioned to be slidably and rotatably received in the bore 22″ defined by the wall 22 c″ of the receiver 20″, as illustrated in FIGS. 37-57.

Notice that edges 112 a″, 112 b″ and 114 a″, 114 b″ of the wall portions 112″ and 114″, respectively, and surfaces 117 a″ (FIG. 35A) and 119 a″ (FIG. 35B) of the joining portions 117″ and 119″, respectively, cooperate with the surface 112 c″ of first curved wall portion 112″ and the surface 114 c″ of the second curved wall portion 114″, respectively, to define the channel 121″ (FIGS. 35C-35E). The guide or sleeve channel 121″ receives the rod 24″ as described herein. The surfaces 112 c″ and 114 c″ could be curved as illustrated in FIGS. 35A-35C or they could be straight or generally planar, as illustrated in FIGS. 35D and 35E.

As illustrated in FIGS. 35D-35E, the joining portions 117″ and 119″ each have a dimension D17. The dimension D17 and the dimension D16 (FIG. 35D) of bore 110″ and shape or radius of head 102 a″ are adapted and dimensioned so that at least a portion of the polyaxial screw head 102 a″ protrudes or extends at least partly into the bore 110″ and into channel 121″ above a plane P5 (FIG. 35E) defined by surfaces 117 a″ (FIG. 35C) and 119 a″ (FIG. 35D). As will be described later herein, this permits or enables the rod 24″ to directly engage and compress against at least a portion, such as a portion or area 120″ (FIG. 36A), of the head 102 a″, so that the rod 24″ can become locked directly against the head 102 a″ when the receiver 20″ is rotated as described herein.

Notice in FIGS. 35A-35B and 36A and 36B that the head 102 a″ has the first engaging surface or contact area 120″, which in the illustration being described is generally centrally located along an axis SA (FIGS. 35A and 36A) of a threaded portion 102 b″ (FIG. 35A) of the screw 102″.

The overall shape or configuration of an outer surface 102 a 1″ (FIG. 36A-36B) of the head 102″ is generally curved, arcuate or spherical. Notice in FIG. 36B that the head 102″ comprises a plurality of recessed areas 122″, 124″, 126″ and 128″ that are separated by or define a plurality of curved portions or walls 130″, 132″, 134″ and 136″ as shown. Notice that the curved walls 130″, 132″, 134″ and 136″ are joined by a generally cylindrical post or portion 138″ that cooperate to define a male member 129″ that extends upwardly (as viewed in FIG. 35A) from a plane P4 (FIG. 35B) defined by the surfaces 140″, 142″, 144″ and 146″ (FIG. 36B).

In the illustration being described, the engaging surface or portion 120″ has a surface 120 a″ that is curved in the illustration being described. The walls 130″, 132″, 134″, and 136″ each have surfaces or portions 150″, 152″, 154″ and 156″, respectively, that are also curved in the illustration being described.

It should be understood that the head 102 a″ may comprise any suitable configuration or surface shape as may be necessary to permit the at least a portion 120″ of the head 102 a″ to engage or be engaged by the rod 24″. Although not shown, if the rod 24″ had a non-curved surface, then it may be desirable to provide a head (not shown) having a shape that is adapted to directly complement and engage the non-curved surface. For example, if the rod 24″ were hexagonal, octagonal, square or rectangular in cross section, then the head 102 a″ may have a mating or engaging portion to facilitate directly engaging the rod 24″ when the receiver 20″ is moved or rotated to the locked position. Moreover, a radius of curvature of each of the surfaces 120 a″, 150″, 152″, 154″ and 156″ may be generally constant, may vary over its surface, or may be non-constant if desired. Also, the curvatures or shapes of the surfaces may be larger or smaller if desired, and they may be different among them.

The surface 105″ may be straight or it may comprise a curvature, arcuate or spherical shape in order to adapt to and complement the curvature or shape of the head 102 a″ and/or surfaces 150″, 152″, 154″ or 156″ as shown.

As illustrated in FIGS. 43 and 44, notice that the rod 24″ is received in the receiving area or channel 22″ in the area 110″ and channel 121″ (FIG. 43). The rod 24″ becomes positioned in the receiver 20″ and against the generally curved or arcuate wall portions 50″ and 52″ of receiver 20″ as shown. After the receiver 20″ is rotated from the unlocked position, illustrated in FIGS. 43 and 44, to a locked position, illustrated in FIGS. 45 and 46, the rod 24″ becomes cammed or urged downward (as viewed in the Figures) until at least a portion of the rod 24″ engages at least a portion of the head 102 a″, such as one or more of the surfaces 120 a″, 150″, 152″, 154″, or 156″ as shown. For example, notice in FIGS. 45 and 46 that the rod 24″ engages the surface 120 a″. Note that the receiver 20″ cams, urges or forces the rod 24″ downward (as viewed in the FIGS. 45 and 46) until the rod 24″ engages the surface 120 a″ and thereby locks the rod 24″ to the head 102″ after the receiver 20″ is rotated to the locked position shown in FIGS. 45 and 46.

As mentioned earlier, the arcuate or curved wall portions 112 c″ and 114 c″ cooperate with the joining portions 117″ and 119″ to define the aperture or bore 110″. As mentioned earlier herein, note that the dimension D16 generally corresponds to or is generally the same as the dimension D18 (FIG. 35E) between the surfaces 112 c″ and 114 c″ of walls 112″ and 114″, respectively, but it could be smaller or larger so that it is adapted and dimensioned to permit at least a portion of the head 102 a″ to be engages by the rod 24″.

The dimensions D16 (FIG. 35D), and D18 (FIG. 35E) and the guide or sleeve member 104″ are selected, adapted and configured to permit at least a portion, such as the engaging portion 120 a″ and/or all of or at least a portion of one or more of the surfaces of 150″, 152″, 154″ and 156″ to extend through the aperture or bore 110″ and into channel 121″ and above the plane P5 (FIG. 35D). Thus, the adaptation or configuration of the guide or sleeve 112″, bore 110″ and channel 112″ permits at least a portion of the head 102 a″ to protrude or extend into the channel 121″ so that it may engage or be engaged by rod 24″ when the receiver 20″ is rotated to the locked position illustrated in FIGS. 45 and 46.

Unlike prior embodiments described herein, notice that no compression member 40 is necessary in this embodiment, and although not shown, the guide or sleeve 104″ is also optional in this embodiment. In the illustration being described, the guide or sleeve 104″ comes into direct contact with the head 102 a″ of the screw 102″ when the receiver 20″ is rotated to the locked position, but the sleeve 104″ itself does not compress against the head 102 a″ to lock the rod 24″ to the head 102 a″ as does the compression member 40″ in the embodiments illustrated in FIGS. 1-34, for example.

It should be understood that the embodiment being described relative to FIGS. 35A-59, may be used with a receiver 20 having channels 32 and 34 of the type shown in FIGS. 1-16E. Alternatively, the embodiment may be used with a receiver 20′ having the channels 32″ and 34″ having the steps or channel areas that are of the type shown in FIGS. 18-34, namely channels 32″ and 34″ that each have a cross-sectional dimension that varies over the length of the channels 32″ and 34″. As mentioned earlier, such shape facilitates providing the intermediate holding area 60″ where the rod 24″ is loosely captured in the channels 32″ and 34″. The use of and installation of the system 100″ is similar to the use and installation of the embodiments earlier relative to FIGS. 1-34, which will now be described.

As with the prior embodiment and as illustrated in FIGS. 1 and 2, one or more of the assemblies or systems 100 may be used during a surgical procedure as shown in FIGS. 58 and 59. For example, the surgeon may use a plurality of receivers 20″ and screws 102″ with a rod 24″ similar to the illustration shown in FIGS. 1 and 2. In the illustration being described relative to the embodiment of FIGS. 35A-59, the surgeon positions the screw 102″ into bore 110″ and screws the screws 102″ for each assembly 100″ into each of the plurality of vertebrae, respectfully, such as vertebrae 14″, 16″ and 18″ illustrated in FIG. 58. He then situates the guide or sleeve 104″ into bore 22″ and generally aligns the channel 121″ of the sleeve or guide 104″ with the receiving channel 26″ of the receiver 20″ as illustrated in FIGS. 37, 38, 43, 44, 49 and 55. The surgeon then inserts a tool 125″ (FIG. 36I) that is capable of rotatably driving the screw 102″ into bone or into the bore 110″ and drives screw 102″ until the bottom 20 b″ of the receiver 20″ engages or is approximately located adjacent to or against its respective vertebrae.

Note that the guide sleeve 104″ is located in the bore 22″ of the receiver 20″ and provides a guide for the rod 24″ to become aligned and positioned in receiver 20″, as illustrated in FIGS. 37, 43-46, 49-51 and 55-57. The walls 112″ and 114″ of the guide or sleeve 104″ perform lateral stabilization and alignment of the rod 24″. It should be understood that when the assembly 100″ is in the unlocked position (as illustrated, for example, in FIGS. 37, 38, 43, 44, 49 and 55), the channels 121″ and 26″ become generally parallel and lie in a common plane P6 (FIG. 38). After the rod 24″ is placed in the channels 26″ and 121″, it is supported by the walls 50″ and 52″ of receiver 20 and between walls 112″ and 114″, as best illustrated in FIGS. 43 and 44. This causes the rod 24″ to be supported slightly above the surfaces 117 a″ (FIG. 35C) and 119 a″ (FIG. 35D). As mentioned earlier, the shape and configuration of screw head 102 a and the dimension of bore 110″ allows for the screw ball or head 102 a″ to protrude through the bore 110″. The lower portion 102 c″ has been further truncated or indented to allow for maximal exposure of the screw-ball.

As mentioned earlier herein, the receiver 20″ may have generally straight channels 32″ and 34″ of the type illustrated in FIGS. 18-32 or channels of varying dimensions of the type illustrated in FIGS. 49-57, in which case the rod 24″ would be positioned in the receiver 20′ as illustrated in FIGS. 49 and 55. For ease of discussion, it will be assumed that receiver 20″ comprises the channels 32″ and 34″ of the type illustrated in FIGS. 37-42.

After the screw(s) 102″ are screwed into the bone a desired distance and the guide or sleeve 104″ is inserted into the receiver 20″, the surgeon aligns the rod 102″ in the receiver 20″ to the desired position relative to the spine, vertebrae or bone and also relative to one or more other receivers 20″, if any, that are being used during the procedure. It should be understood that the screws 102″ and the position of the vertebrae 14″-18″, relative to each other may be adjusted by the surgeon. Once the bones 14″-18″ are adjusted and the angular or polyaxial position of the receiver 20″ is adjusted, the rod 102″ is adjusted within the receiver 20″ and in the guide sleeve 104″. The surgeon or technician may then lock the receiver 20″ to the rod 24″ by rotating or turning the receiver 20″ with the tool, such as a flat-head screw driver (not shown), placed in the slot 26″. This causes the rod 24″ to directly engage at least a portion of the screw head 102 a″, such as surfaces or portions 120 a″, 150″, 152″, 154″ or 156″, thereby causing the rod 24″ to become locked or fixed onto the screw 102″. This causes the receiver 20″ to become affixed to its respective bone, such as spinal bones 14-18 (FIG. 1).

As illustrated in FIGS. 37-42 and 49-57, notice that as the receiver 20″ is rotated, the rod 24″ is cammed, forced or urged downward (as viewed in FIGS. 43-46) and in a direction parallel to the axis SA (FIG. 43) until the rod 24″ comes into direct engagement with the at least a portion of the head 102 a″. In the illustration being described, notice in FIGS. 45 and 46 that the rod 24″ comes into direct contact and engagement with the portion in 120″ of the head 102 a″.

FIGS. 39 and 40 illustrate the rod 24″ situated in the receiver 20″ after it is rotated between unlocked and locked positions. FIGS. 50 and 56 also illustrate an intermediate position after the receiver 20″ has been rotated slightly and the rod 24″ is captured in the channels 32″ and 34″ and upon rotation of receiver 20″, being urged downward toward the head 102 a″ of the screw 102″. Finally, the FIGS. 41, 42, 45 and 46 illustrate the assembly 100″ after the receiver 20″ has been rotated clockwise in the illustration, showing the rod 24 directly engaging at least portion, such as portion 120 a″, of the head 102 a″ of the screw 102″. As best illustrated in FIGS. 37-42, after the receiver 20″ is rotated from the unlocked position (shown in FIGS. 37, 38, 43 and 44) to the locked position (shown in FIGS. 41, 42, 45 and 46), the rod 24″ engages, compresses and becomes locked against at least a portion, such as portion 120 a″, of the head 102 a″ of the screw 102″.

If the receiver 20″ comprises the channels 32″ and 34″ having the configurations of the type illustrated in FIGS. 18-34, then the operation is similar. In this regard, the screw 102″ is received in the bore 110″ and the guide or sleeve 104″ is situated in the bore 110″ after which the screw 102 is driven by a tool, such as tool 125″ in FIG. 36I, into bone, such as vertebrae 14″. In other words, as with the embodiment described earlier herein relative to FIGS. 18-34, the rod 24″ is loosely captured in the channel 32″ and 34″ as illustrated. In FIGS. 49 and 55 recall that the channels 32″ and 34″ each have the introducing area 60 a″, the intermediate holding area 60 b″ and the locking area 60 c″. As illustrated in FIGS. 49, 52 and 55, the guide sleeve 104″ and receiver 20″ are aligned such that their respective channels 121″ and 26″, respectively, become generally aligned so that the rod 24″ may be inserted therein. As illustrated in FIGS. 50, 53 and 56, as the receiver 20″ is rotated about its axis RA (FIG. 56), the rod 24″ becomes captured in the intermediate holding or receiving area 60 b″ as illustrated in FIGS. 50 and 56. The intermediate holding area 60 b″ in the channels 32′ and 34′ enable the intermediate step between the initial rod 24″ insertion and final rod 102″ locking.

As with the embodiment described earlier herein, relative to FIGS. 18-34, the rod 24″ capturing step during which the rod 24″ is loosely captured in the receiver 20″, but is not yet rigidly locked in place against at least a portion 120 a″ of screw head 102 a″. This allows the surgeon greater ease and flexibility when he adjusts the relative position of the rod relative to the screw head 102 a″. For example, and as mentioned earlier herein, the surgeon may cause or move the screws 102″ closer together (compression) or further apart and then rotate the receiver 20″ using the tool, such as a screwdriver placed in the slot 26″, to lock the rod 24″ in direct engagement with the screw head 102 a″.

Notice in FIGS. 51, 54 and 57, the receiver 20″ has been rotated to the locked position, thereby locking the rod 24″ directly to at least a portion, such as portion 120 a″, of the screw head 102″.

It should be understood, however, that as with prior embodiments, the receiver 20″ may be situated such that its axis RA is not coaxial with the screw axis SA (FIG. 43) of screw 102″. The relative position of the receiver 20″ and the head 102″ enables the polyaxial position of the receiver 20″ and the corresponding position of the rod 24″ relative to the head 102 a″ to be adjusted by the surgeon during use. For example, notice the receiver 20″ may be tilted or pivoted as shown in FIGS. 47 and 48, after the rod 24″ is positioned in the desired position, the receiver 24″ is rotated from, for example, the unlocked position and intermediate positions, illustrated in FIGS. 49 and 50, to the locked position illustrated in FIGS. 51 and 57, whereupon the rod 24″ engages and compresses against at least a portion of the head 102 a″ as described herein. Notice that after the receiver 20″ has been moved or rotated to the locked position, the rod 24″ engages, compresses and becomes locked against the at least a portion of the screw head 102 a″, such as portions or surfaces 120 a″, 150″, 152″, 154″ and 156″ (FIG. 36A). The receiver 20″ remains in the tilted position relative to the head 102 a″.

Advantageously, the screw head 102 a″ is configured and adapted to have a desired shape, such as a curved, arcuate or spherical shape or other desired shape, so that the receiver 20″ can be positioned in a desired polyaxial position, even if its axis RA (FIG. 56) is not coaxial with the axis SA (FIG. 43) of the screw 102″. This permits the polyaxial position of the rod 24″ relative to the screw head 102 a″ to be changed. In this regard, note in FIGS. 35A, 35B, 45 and 46 that the screw 102″ has a truncated or indented area 102 c″ to permit or allow for maximal exposure of the screw ball or head 102 a″, which in turn facilitates a wide range of polyaxial movement

It should be appreciated that the recesses 122″, 124″, 126″ and 128″ (FIG. 36B) could also comprise more or fewer recesses or apertures and could comprise other configurations or shapes. FIGS. 36C-36D, 36E-36F and 36G-36H illustrate other representative or illustrative configurations of the head 102 a″ of the screw 102″ that also permit polyaxial movement and locking of the receiver 20″ to the rod 24″. Notice, for example, a screw 170″ (FIG. 36C) has a head 172 having a shape or surface that is also curved, arcuate or spherical. However, the recessed areas 174″ and 176″ provide at least one or a plurality of female openings that receive elongated engagement members 180″, 182″ of a tool 184″ (FIG. 36J) used to rotate the screw 102″.

FIGS. 36E and 36F Illustrate a screw head 188″ having a square aperture 189″ in the curved or spherical head 188 a″ (FIG. 36E) for receiving a tool 178″ (FIG. 36K) having a square hollow tip 178 a″. Similarly, a screw head 190″ (FIGS. 36G and 36H) having a hexagonal aperture 192″ for receiving a hollow male hexagonal tip 194″ (FIG. 36L) of a tool 196″ (FIG. 36L) for rotating the head 190 a″ and the screw 190″. Notice that the heads 188″ and 190″ in the embodiments illustrated in FIGS. 36E-36H each have surfaces 188 a 1″ and 190 a 1″, respectively, that are arcuate, curved or spherical and also provide a plurality of areas, portions, surfaces or surface area contact points against which the rod 24″ may be compressed or engaged after the receiver 20″ has been rotated to the locked position mentioned herein.

Advantageously, this system and method provides apparatus, method and means for providing a capless and polyaxial positionable and moveable receiver 20″ which reduces or eliminates the need for a compression member, such as the compression member 40″ of the type described earlier herein relative to the embodiments shown in FIGS. 1-34. In this embodiment, the guide sleeve 104″ provides means for receiving the rod 24″ and guiding it into the receiver 20″ and also for guiding the rod 24″ toward the head 102″ as the receiver 20″ is moved or rotated from the unlocked or intermediate positions shown, for example, 43 and 44 to the locked position 45 and 46, respectively. Thus, in the illustration being described, the rod 24″ directly engages the head 102 a″ and becomes locked there against.

Advantageously, this system and method provide a capless multiaxial screw which eliminates the need for caps or screws or threads of the type used in the prior art. This system and method combine a very simplified yet effective means for locking an elongated member or rod to a screw and bones, such as spinal bones or other human bones, in the manner described and shown herein.

While the apparatus, system and method herein described, and the form of apparatus for carrying this method into effect, constitute several illustrative embodiments of this invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the inventions, which is defined in the appended claims. 

1. A capless multiaxial screw system comprising: a receiver comprising a receiver end comprising a receiver bore for receiving a threaded portion of a screw having a screw head; and a sleeve having a sleeve end for situating against at least a portion of said screw head after said threaded portion is received in said receiver bore, said sleeve having a sleeve bore associated with said sleeve end; said receiver having a channel for receiving an elongated member; said sleeve being adapted to permit said elongated member to engage said at least of portion of said screw head when said elongated member is received in said channel and said receiver is rotated to a locked position.
 2. The capless multiaxial screw system as recited in claim 1 wherein said sleeve end comprises an outer end surface that is tapered or concave, said outer end surface engaging said at least a portion of said screw head.
 3. The capless multiaxial screw system as recited in claim 1 wherein said sleeve end comprises an inner end surface, said at least a portion of said screw head extending through said sleeve bore beyond said inner end surface when said receiver is in said locked position.
 4. The capless multiaxial screw system as recited in claim 1 wherein said receiver comprises a plurality of channels for receiving said elongated member.
 5. The capless multiaxial screw system as recited in claim 4 wherein each of said plurality of channels defines an intermediate area for capturing said elongated member to facilitate adjusting a position of said elongated member before it is locked in said receiver.
 6. The capless multiaxial screw system as recited in claim 5 wherein said plurality of channels are defined by a first surface and a second surface, each of said plurality of channels having an intermediate step for defining said intermediate area.
 7. The capless multiaxial screw system as recited in claim 6 wherein at least one of said first or second surfaces is not planar.
 8. The capless multiaxial screw system as recited in claim 1 wherein said channel is a helical channel defined by at least one surface of said receiver.
 9. The capless multiaxial screw system as recited in claim 1 wherein said sleeve end comprises a generally concave or semispherical seat, at least a second portion of said screw head having a curvature that generally complements said generally concave or semispherical seat.
 10. The capless multiaxial screw system as recited in claim 1 wherein said channel comprises a receiving area that is generally parallel to an axis of said receiver and comprises a locking area that spirals about said axis of said receiver when moving in an axial direction.
 11. The capless multiaxial screw system as recited in claim 10 wherein said locking area extends in a direction that is generally not parallel to said axis of said receiver.
 12. The capless multiaxial screw system as recited in claim 1 wherein said receiver comprises at least one camming surface that cooperates with an opposing surface for defining said channel, said at least one camming surface facilitates compressing said elongated member directly against said at least a portion of said screw head.
 13. The capless multiaxial screw system as recited in claim 1 wherein said receiver comprises a plurality of camming surfaces that cooperate with a plurality of opposing surfaces, respectively, to define said channel, said plurality of camming surfaces for camming against said elongated member and forcing it into compression against said at least a portion of said screw head.
 14. The capless multiaxial screw system as recited in claim 13 wherein said locking channel comprises a first locking channel area and a second locking channel area, said receiver comprises a first camming surface generally opposed to a first opposing surface to define said first locking channel area and a second camming surface generally opposed to a second opposing surface to define said second locking channel area, said first and second camming surfaces camming against said elongated member to cause said elongated member to apply a compressive force against said screw head when said receiver is rotated.
 15. The capless multiaxial screw system as recited in claim 1 wherein said channel comprises a lock member associated therewith for facilitating retaining said receiver in a locked position.
 16. The capless multiaxial screw system as recited in claim 15 wherein said lock member cooperates with an end wall of said channel to define a locking area at which said receiving member is locked when it is in said locked position.
 17. The capless multiaxial screw system as recited in claim 1 wherein said channel lies in a first plane that is generally planar and said receiver further comprising a locking channel that lies in a second plane that is non-planar.
 18. The capless multiaxial screw system as recited in claim 1 wherein said receiver comprises a locking channel that spirals about an axis of said retainer.
 19. The capless multiaxial screw system as recited in claim 1 wherein said receiver comprises a seat, said screw head having a screw head end that is generally spherical or semispherical and said seat is adapted to receive and complement said screw head end.
 20. The capless multiaxial screw system as recited in claim 1 wherein said screw head comprises a plurality of recessed areas in at least a portion of said screw head adapted to receive a tool for driving said screw.
 21. The capless multiaxial screw system as recited in claim 1 wherein said screw head comprises a simple recessed area adapted to receive a tool for driving said screw.
 22. The capless multiaxial screw system as recited in claim 1 wherein said at least a portion of said screw head comprises an outer surface that is arcuate, curved, semispherical or spherical.
 23. The capless multiaxial screw system as recited in claim 22 wherein said outer surface is spherical.
 24. The capless multiaxial screw system as recited in claim 1 wherein said sleeve end is adapted to permit direct engagement or compression of said elongated member against said at least a portion of said screw head.
 25. The capless multiaxial screw system as recited in claim 1 wherein said screw head is adapted to permit point contact and compression of said elongated member against said at least a portion of said screw head when a screw axis of said screw is not coaxial with a receiver axis of said receiver.
 26. The capless multiaxial screw system as recited in claim 3 wherein said sleeve bore is adapted to permit said at least a portion of said screw head to extend into said sleeve bore a predetermined distance such that it extends into said channel.
 27. The capless multiaxial screw system as recited in claim 1 wherein said sleeve comprises two generally opposing walls that stabilize and align said elongated member in said receiver.
 28. The capless multiaxial screw system as recited in claim 27 wherein said at least a portion of said screw head comprises an outer surface that is arcuate, curved, semispherical or spherical in cross section.
 29. A bone fixation assembly comprising: a receiver having a receiver bore for receiving a screw having a screw head and a receiver channel in communication with said receiver bore for receiving an elongated member; and a stabilizer adapted to be received in said receiver bore, said stabilizer having a stabilizer channel and a stabilizer bore through said stabilizer, said stabilizer adapted to permit direct contact between at least a portion of said screw head and said elongated member; said receiver being capable of rotating relative to said elongated member after said elongated member is received in said receiver channel to force said elongated member into contact with said at least a portion of said screw head.
 30. The bone fixation assembly as recited in claim 29 wherein said receiver comprises at least one engaging surface for engaging said elongated member and for locking said elongated member to said at least a portion of said screw head when said receiver is rotated to a locked position.
 31. The bone fixation assembly as recited in claim 29 wherein said receiver is generally cylindrical and said receiver bore extends along an axis of said receiver, said receiver comprising a first locking aperture in communication with said receiver bore and a second locking aperture in communication with said receiver bore; said first and second locking apertures cooperating to define a locking channel.
 32. The bone fixation assembly as recited in claim 31 wherein said locking channel is defined by a first channel in a wall of said receiver and a second channel in said wall of said receiver, said first and second channels being generally opposed.
 33. The bone fixation assembly as recited in claim 32 wherein said first channel and said second channel extend away from said receiver channel about a receiver axis of said receiver such that rotation of the receiver will cause said elongated member to move to a locked position whereupon it engages said at least a portion of said screw head.
 34. The bone fixation assembly as recited in claim 32 wherein said first channel and said second channel spiral in a common direction about a receiver axis of said receiver.
 35. The bone fixation assembly as recited in claim 29 wherein said receiver comprises a wall that lies in a generally circular or arcuate plane about a receiver axis of said receiver and said receiver channel being by said wall.
 36. The bone fixation assembly as recited in claim 29 wherein said screw head comprises a plurality of recessed areas.
 37. The capless multiaxial screw system as recited in claim 29 wherein said screw head comprises a single recessed area adapted to receive a tool for driving the screw.
 38. The bone fixation assembly as recited in claim 29 wherein an outer surface of said at least a portion of said screw head is arcuate, curved, spherical or semispherical in cross section.
 39. The bone fixation assembly as recited in claim 29 wherein an outer surface of said at least a portion of said screw head is arcuate or spherical at said at least a portion of said screw head.
 40. The bone fixation assembly as recited in claim 39 wherein said screw has a truncated area for permitting maximal polyaxial movement of said receiver relative to said screw head.
 41. The bone fixation assembly as recited in claim 29 wherein said stabilizer bore of said stabilizer is adapted to permit point contact of said elongated member against said at least a portion of said screw head.
 42. The bone fixation assembly as recited in claim 39 wherein said stabilizer bore of said stabilizer is adapted to permit point contact of said elongated member against said at least a portion of said screw head.
 43. The bone fixation assembly as recited in claim 29 wherein said screw head and said stabilizer bore are adapted to permit point contact of said elongated member against said at least a portion of said screw head and when a screw axis of said screw is not coaxial with a receiver axis of said receiver.
 44. The bone fixation assembly as recited in claim 29 wherein said stabilizer bore is adapted to permit said at least a portion of said screw head to extend into said receiver bore a predetermined distance.
 45. The bone fixation assembly as recited in claim 29 wherein said stabilizer comprises an inner end surface, said at least a portion of said screw head extends beyond said inner end surface and into said stabilizer bore when said elongated member is in a locked position in said receiver.
 46. The bone fixation assembly as recited in claim 29 wherein said stabilizer comprises a first wall and a generally opposed second wall for defining a stabilizer receiving area or channel for receiving said elongated rod.
 47. The bone fixation assembly as recited in claim 46 wherein said stabilizer bore is in communication with said stabilizer receiving area, said stabilizer bore being adapted to permit said at least a portion of said screw head to be received in said stabilizing bore so that said elongated member directly engages or is engaged by said at least a portion of said screw head when said receiver is rotated to a locked position.
 48. The bone fixation assembly as recited in claim 47 wherein said stabilizer comprises a generally cylindrical wall that defines said stabilizer bore.
 49. The bone fixation assembly as recited in claim 48 wherein said generally cylindrical wall comprises an inner diameter that generally corresponds to a distance between said first and second walls.
 50. An intermediate member for use with a polyaxial screw having a head that is generally spherical comprising: a body having a bore; and a channel for receiving an elongated member; said bone being adapted to permit at least a portion of a screw head of the polyaxial screw to enter into said bore.
 51. The intermediate member as recited in claim 50 wherein a width of said channel is at least as large as a radius of said bore.
 52. The intermediate member as recited in claim 50 wherein said intermediate member comprises an end having a frusto-conical, or spherical or semispherical surface for engaging said screw head.
 53. The intermediate member as recited in claim 50 wherein said intermediate member comprises an end having an opening adapted to permit said elongated member to engage or be engaged by at least one portion of said screw head.
 54. A bone fixation assembly comprising: a receiver having a bore for receiving a screw having a screw head; and an intermediate member dimensioned to be received in said bore and having a first end and a second end; said receiver comprising an integral rotary lock for forcing and locking an elongated member directly against said screw head when said receiver is rotated.
 55. The bone fixation assembly as recited in claim 54 wherein said integral rotary lock comprises a continuous channel for receiving said elongated member and for urging said elongated member toward said screw head when said receiver is rotated.
 56. The bone fixation assembly as recited in claim 54 wherein said integral rotary lock comprises a first channel that extends about a receiver axis in a first direction and a second channel that extends about said receiver axis in a second direction and a receiver channel coupling said first and second channels.
 57. The bone fixation assembly as recited in claim 56 wherein said first and second directions extend away from said receiver channel about a receiver axis of said receiver such that rotation of said receiver will move said elongated member from an unlocked position to a locked position.
 58. The bone fixation assembly as recited in claim 56 wherein said receiver channel lies in a plane that generally extends along an axis of said receiver.
 59. The bone fixation assembly as recited in claim 56 wherein said first and second channels spiral about said receiver axis.
 60. The bone fixation assembly as recited in claim 56 wherein said first and second channels lie in imaginary planes that intersect an axis of said receiver at acute angles.
 61. The bone fixation assembly as recited in claim 56 wherein said receiver channel lies in a receiver plane, said first channel lies in a first plane and said second channel lies in a second plane, each of said first and second planes intersecting said receiver plane at an acute angle that extends toward a bone when said screw is screwed into the bone.
 62. The bone fixation assembly as recited in claim 54 wherein said receiver comprises a removable intermediate member for stabilizing said elongated member.
 63. The bone fixation assembly as recited in claim 62 wherein said removable intermediate member comprises an end having an opening, said screw head and said opening being adapted to enable said elongated member to contact at least one portion of said screw head.
 64. The bone fixation assembly as recited in claim 54 wherein said screw head is generally spherical.
 65. The bone fixation assembly as recited in claim 62 wherein said screw head is generally spherical.
 66. A bone fixation assembly comprising: a receiver having an opening for receiving a screw having a screw head; and an intermediate member dimensioned to be received in said opening and having an intermediate member receiving channel for receiving an elongated member and a screw head receiving opening adapted to receive at least a portion of said screw head; said receiver comprising a receiver channel for receiving said elongated member, said receiver channel compressing said elongated member against said screw head when said receiver is rotated from an unlocked position to a locked position.
 67. The spiral fixation assembly as recited in claim 66 wherein said receiver channel comprises a locking channel that spirals about an axis of said receiver.
 68. The spiral fixation assembly as recited in claim 67 wherein said locking channel provides a bayonet connection between said elongated member and said screw.
 69. The bone fixation assembly as recited in claim 66 wherein said receiving channel comprises at least a portion that lies in a first plane and said intermediate member receiving channel comprises at least a portion that lies in a second plane, said second plane and said first plane being generally parallel when said elongated member is in said unlocked position and generally perpendicular when said elongated member is in said locked position.
 70. The bone fixation assembly as recited in claim 66 wherein when said receiver is rotated from said unlocked position to said locked position, said elongated member directly engages said at least a portion of said screw head and becomes situated closer to said screw compared to when said elongated member is in said unlocked position.
 71. The bone fixation assembly as recited in claim 70 wherein said receiver channel is in communication with a locking channel so that when said receiver is in said unlocked position, said receiving channel becomes generally aligned with said intermediate member receiving channel in said intermediate member.
 72. The bone fixation assembly as recited in claim 66 wherein said receiver channel is generally perpendicular to an elongated member axis of said elongated member when said receiving member is in said locked position.
 73. The bone fixation assembly as recited in claim 66 wherein said receiver channel comprises a locking channel that spirals from a first end of said receiver toward a second end of said receiver.
 74. The bone fixation assembly as recited in claim 73 wherein said locking channel defines a helix.
 75. The bone fixation assembly as recited in claim 66 wherein said receiver channel extends from an end of said receiver in a direction that is generally parallel to an axis of said receiver and further comprises a locking channel that extends at least partially about said axis of said receiver.
 76. The bone fixation assembly as recited in claim 66 wherein said intermediate member receiving channel becomes generally aligned with said receiver channel when said elongated member is received in said receiver and said receiver channel and said intermediate member receiving channel become non-aligned when said receiver is rotated to said locked position.
 77. The bone fixation assembly as recited in claim 66 wherein said receiver channel comprises a locking channel, said receiver comprising at least one camming surface that cooperates with an opposing surface that cooperates to define said receiver channel, said at least one camming surface camming against said elongated member to move said elongated member against said screw head when said receiver is rotated.
 78. The bone fixation assembly as recited in claim 66 wherein said receiver comprises a plurality of camming surfaces that cooperate with a plurality of opposing surfaces, respectively, to define a locking channel, said plurality of camming surfaces camming against said elongated member to cause said elongated member to apply a compressive force against said screw head when said receiver is rotated.
 79. The bone fixation assembly as recited in claim 66 wherein said receiver comprises a locking channel comprising a first locking channel area and a second locking channel area said receiver comprises a first camming surface generally opposed to a first opposing surface to define said first locking channel area and a second camming surface generally opposed to a second opposing surface to define said second locking channel area, said first and second camming surfaces camming against said elongated member to force said elongated member to apply a compressive force against said screw head when said receiver is rotated.
 80. The bone fixation assembly as recited in claim 79 wherein said receiver comprises a detent or protrusion or a plurality of detents or protrusions in communication with said locking channel.
 81. The bone fixation assembly as recited in claim 79 wherein said receiver comprises a surface that defines an end wall of said locking channel to define a locking area at which said elongated member is locked when it is in said locked position.
 82. The bone fixation assembly as recited in claim 66 wherein said receiver comprises a locking channel, said receiver channel lies in a first plane that is generally planar and said locking channel lies in a second plane that is non-planar.
 83. The bone fixation assembly as recited in claim 82 wherein said second plane spirals about an axis of said receiver.
 84. The bone fixation assembly as recited in claim 82 wherein said locking channel extends in a direction that is non-axial relative to an axis of said receiver.
 85. The bone fixation assembly as recited in claim 66 wherein said screw head is generally arcuate, spherical, semispherical or curved and said intermediate member comprises an end having an outer end surface that is generally complementary in shape and adapted to receive said screw head.
 86. The bone fixation assembly as recited in claim 66 wherein said screw head comprises a plurality of recessed areas surrounding said at least a portion of said screw head.
 87. The bone fixation assembly as recited in claim 66 wherein said at least a portion of said screw head is spherical in cross section.
 88. The bone fixation assembly as recited in claim 66 wherein said at least a portion of said screw head is spherical in cross section at an area where said elongated member directly engages said screw head.
 89. The bone fixation assembly as recited in claim 66 wherein said outer surface of said screw head is adapted to permit point contact of said elongated member directly against said at least a portion of said screw head.
 90. The bone fixation assembly as recited in claim 66 wherein said screw head is adapted to permit point contact of said elongated portion against said at least a portion of said screw head when a screw axis of said screw is not coaxial with a receiver axis of said receiver.
 91. The bone fixation assembly as recited in claim 66 wherein said intermediate member comprising an end having an opening adjusted to permit an engaging portion of said screw head to extend into said receiver opening a predetermined distance.
 92. The bone fixation assembly as recited in claim 66 wherein said intermediate member comprises a bottom surface, said at least a portion of said screw extending beyond said bottom surface and into said receiver channel when said elongated member is in said locked position.
 93. The bone fixation assembly as recited in claim 66 wherein said intermediate member comprises an end having an outer end surface that is frusto-conical.
 94. The bone fixation assembly as recited in claim 66 wherein said screw head comprises an outer surface and at least one tool aperture or area for receiving a tool.
 95. A capless multiaxial screw system comprising: a screw having a threaded portion and a screw head; a receiver having a receiver bore for receiving said threaded portion and a receiving channel for receiving an elongated member, said receiver further comprising a locking channel in communication with said receiving channel; an intermediate member adapted to be situated in said receiver bore, said intermediate member comprising an intermediate member bore for receiving at least a portion of said screw head; and said intermediate member bore and said screw head being adapted to permit said at least a portion of said screw head to extend into said locking channel so that said elongated member may engage and compress against said at least a portion of said screw head when said elongated member is received in said receiving channel and said receiver is rotated.
 96. The capless multiaxial screw system as recited in claim 95 wherein said locking channel comprises a plurality of channels, each of said plurality of channels defining an intermediate area for capturing said elongated member to facilitate adjusting a position of said elongated member before it is locked in said receiver.
 97. The capless multiaxial screw system as recited in claim 96 wherein each of said plurality of channels are defined by a first surface and a second surface, each of said plurality of channels having an intermediate step on at least one of said first surface or said second surface for defining said intermediate area.
 98. The capless multiaxial screw system as recited in claim 97 wherein at least one of said first and second surfaces is not planar.
 99. The capless multiaxial screw system as recited in claim 95 wherein said locking channel is a helical channel defined by at least one surface in a body of said receiver.
 100. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member comprises an end having a first side comprising a generally concave seat, at least a second portion of said screw head having a curvature that generally complements said generally concave seat.
 101. The capless multiaxial screw system as recited in claim 95 wherein said receiving channel is generally parallel along an axis of said receiver and said locking channel spirals about said axis of said receiver when moving in an axial direction.
 102. The capless multiaxial screw system as recited in claim 95 wherein said receiving channel extends from an end of said receiver in a direction that is generally parallel to said axis of said receiver and said locking channel extends in a direction that is generally not parallel to said axis of said receiver.
 103. The capless multiaxial screw system as recited in claim 95 wherein said receiver comprises at least one camming surface that cooperates with an opposing surface to define said locking channel, said at least one camming surface forcing said elongated member against said at least a portion of said screw head.
 104. The capless multiaxial screw system as recited in claim 95 wherein said receiver comprises a plurality of camming surfaces that cooperate with a plurality of opposing surfaces, respectively, to define said locking channel, said plurality of camming surfaces camming against said elongated member to lock said receiver to said at least a portion of said screw head.
 105. The capless multiaxial screw system as recited in claim 95 wherein said locking channel comprises a first locking channel area and a second locking channel area, said receiver comprises a first camming surface generally opposed to a first opposing surface to define said first locking channel area and a second camming surface generally opposed to a second opposing surface to define said second locking channel area, said first and second camming surfaces camming against said elongated member to force said elongated member against said at least a portion of said screw head when said receiver is rotated.
 106. The capless multiaxial screw system as recited in claim 95 wherein said receiving channel lies in a first plane that is generally planar and said locking channel lies in a second plane that is non-planar.
 107. The capless multiaxial screw system as recited in claim 106 wherein said second plane spirals about an axis of said receiver.
 108. The capless multiaxial screw system as recited in claim 95 wherein said locking channel spirals about an axis of said receiver.
 109. The capless multiaxial screw system as recited in claim 95 wherein said receiver comprises a seat defining a seat area said screw head being generally spherical, said seat being adapted to receive and complement said screw head.
 110. The capless multiaxial screw system as recited in claim 95 wherein said screw head comprises a plurality of recessed areas for receiving a tool used to turn said screw.
 111. The capless multiaxial screw system as recited in claim 95 wherein said at least a portion of said screw head is spherical or semispherical.
 112. The capless multiaxial screw system as recited in claim 95 wherein said at least a portion of said screw head is arcuate or spherical in cross section.
 113. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member comprises a seat defining a seat area adapted to permit point contact between said elongated member and said at least a portion of said screw head.
 114. The capless multiaxial screw system as recited in claim 95 wherein said screw head and said screw head receiving opening are adapted to permit point contact of said elongated member against said at least a portion of said screw head when a screw axis of said screw is not coaxial with a receiver axis of said receiver.
 115. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member comprises an end, said intermediate member bore being adapted to permit said at least a portion of said screw head to extend into said locking channel a predetermined distance.
 116. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member comprises a first wall and a generally opposed second wall for defining an intermediate member receiving area for receiving said elongated member.
 117. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member bore is in communication with said intermediate member receiving area, said intermediate member bore being dimensioned to permit said at least a portion of said screw head to be received in both said receiver bore and said intermediate member bore so that when said receiver is rotated, said elongated member engages and locks against said at least a portion of said screw head.
 118. The capless multiaxial screw system as recited in claim 95 wherein said intermediate member is generally cylindrical and defined by a generally cylindrical wall, an inner diameter of said generally cylindrical wall being greater than a diameter of said elongated member.
 119. A capless multiaxial screw fixation assembly comprising: a screw having a threaded portion and a screw head; a receiver having an aperture for receiving said threaded portion and a receiving channel for receiving an elongated member, said receiving channel further comprising a locking channel in communication with said receiving channel; and a guide for situating in said bore, said guide comprising: a second receiving channel associated with a first end of said guide and a seat area associated with a second end of said guide; said guide being adapted to permit at least a portion of said screw head to extend into said receiving channel and said second receiving channel so that said elongated member may engage said screw head to lock or compress said elongated member to said screw when said elongated member is received in said first and second receiving channels and said receiver is rotated from an unlocked position to a locked position.
 120. A bone fixation assembly comprising: a receiver having a receiver bore for receiving a screw having a screw head, said receiver further comprising a locking channel and a receiving channel in communication with said locking channel; and an intermediate member dimensioned to be received in said receiver bore, said intermediate member comprising a body having a first end having an intermediate member channel and a second end having an intermediate member opening; said intermediate member opening being adapted to permit at least a portion of said screw head to engage an elongated member after said elongated member is received in said receiving channel, said locking channel and said intermediate member channel and said receiver is moved to a locked position.
 121. The bone fixation assembly as recited in claim 120 wherein said intermediate member comprises a pair of generally opposed walls that cooperate with said second end to define stabilize and align the elongated member in said receiver channel.
 122. The bone fixation assembly as recited in claim 121 wherein said intermediate member bore is generally cylindrical and comprises a diameter substantially the same as a distance between said pair of generally opposed walls.
 123. A method for stabilizing one or more bones, said method comprising the steps of: placing an elongated member into a receiving channel of said receiver and channel of said intermediate member; and rotating said receiver to cause said elongated member to directly engage at least a portion of said screw head. 